From: Tom Lendacky <thomas.lendacky@amd.com>

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

VMGEXIT is a new instruction used for Hypervisor/Guest communication when
running as an SEV-ES guest. A VMGEXIT will cause an automatic exit (AE)
to occur, resulting in a #VMEXIT with an exit code value of 0x403.

Provide the necessary support to execute the VMGEXIT instruction, which
is "rep; vmmcall".

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 MdePkg/Library/BaseLib/BaseLib.inf       |  2 ++
 MdePkg/Include/Library/BaseLib.h         | 14 +++++++++++
 MdePkg/Library/BaseLib/Ia32/GccInline.c  | 17 +++++++++++++
 MdePkg/Library/BaseLib/X64/GccInline.c   | 17 +++++++++++++
 MdePkg/Library/BaseLib/Ia32/VmgExit.nasm | 31 +++++++++++++++++++++++
 MdePkg/Library/BaseLib/X64/VmgExit.nasm  | 32 ++++++++++++++++++++++++
 6 files changed, 113 insertions(+)
 create mode 100644 MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
 create mode 100644 MdePkg/Library/BaseLib/X64/VmgExit.nasm

diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf
index 3586beb0ab5c..14b3f5721101 100644
--- a/MdePkg/Library/BaseLib/BaseLib.inf
+++ b/MdePkg/Library/BaseLib/BaseLib.inf
@@ -152,6 +152,7 @@ [Sources.Ia32]
   Ia32/ARShiftU64.c | MSFT
   Ia32/EnableCache.c | MSFT
   Ia32/DisableCache.c | MSFT
+  Ia32/VmgExit.nasm | MSFT
 
 
   Ia32/GccInline.c | GCC
@@ -286,6 +287,7 @@ [Sources.X64]
   X64/ReadCr2.nasm| MSFT
   X64/ReadCr0.nasm| MSFT
   X64/ReadEflags.nasm| MSFT
+  X64/VmgExit.nasm | MSFT
 
 
   X64/Non-existing.c
diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index 2a75bc023f56..80bd5cf57a72 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -7880,6 +7880,20 @@ AsmLfence (
   VOID
   );
 
+/**
+  Executes a VMGEXIT instruction (VMMCALL with a REP prefix)
+
+  Executes a VMGEXIT instruction. This function is only available on IA-32 and
+  x64.
+
+**/
+VOID
+EFIAPI
+AsmVmgExit (
+  VOID
+  );
+
+
 /**
   Patch the immediate operand of an IA32 or X64 instruction such that the byte,
   word, dword or qword operand is encoded at the end of the instruction's
diff --git a/MdePkg/Library/BaseLib/Ia32/GccInline.c b/MdePkg/Library/BaseLib/Ia32/GccInline.c
index 5287200f8754..55d2e12bcdc9 100644
--- a/MdePkg/Library/BaseLib/Ia32/GccInline.c
+++ b/MdePkg/Library/BaseLib/Ia32/GccInline.c
@@ -1763,3 +1763,20 @@ AsmFlushCacheLine (
 }
 
 
+/**
+  Executes a VMGEXIT instruction.
+
+  Executes a VMGEXIT instruction. This function is only available on IA-32 and
+  X64.
+
+**/
+VOID
+EFIAPI
+AsmVmgExit (
+  VOID
+  )
+{
+  __asm__ __volatile__ ("rep; vmmcall":::"memory");
+}
+
+
diff --git a/MdePkg/Library/BaseLib/X64/GccInline.c b/MdePkg/Library/BaseLib/X64/GccInline.c
index 154ce1f57e92..17539caa0798 100644
--- a/MdePkg/Library/BaseLib/X64/GccInline.c
+++ b/MdePkg/Library/BaseLib/X64/GccInline.c
@@ -1798,3 +1798,20 @@ AsmFlushCacheLine (
 }
 
 
+/**
+  Executes a VMGEXIT instruction.
+
+  Executes a VMGEXIT instruction. This function is only available on IA-32 and
+  X64.
+
+**/
+VOID
+EFIAPI
+AsmVmgExit (
+  VOID
+  )
+{
+  __asm__ __volatile__ ("rep; vmmcall":::"memory");
+}
+
+
diff --git a/MdePkg/Library/BaseLib/Ia32/VmgExit.nasm b/MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
new file mode 100644
index 000000000000..babc1bf437f2
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Ia32/VmgExit.nasm
@@ -0,0 +1,31 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2019, Advanced Micro Device, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   VmgExit.Asm
+;
+; Abstract:
+;
+;   AsmVmgExit function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; AsmVmgExit (
+;   VOID
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmVmgExit)
+ASM_PFX(AsmVmgExit):
+    rep; vmmcall
+    ret
+
diff --git a/MdePkg/Library/BaseLib/X64/VmgExit.nasm b/MdePkg/Library/BaseLib/X64/VmgExit.nasm
new file mode 100644
index 000000000000..173e12c36054
--- /dev/null
+++ b/MdePkg/Library/BaseLib/X64/VmgExit.nasm
@@ -0,0 +1,32 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2019, Advanced Micro Device, Inc. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   VmgExit.Asm
+;
+; Abstract:
+;
+;   AsmVmgExit function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; VOID
+; EFIAPI
+; AsmVmgExit (
+;   VOID
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(AsmVmgExit)
+ASM_PFX(AsmVmgExit):
+    rep; vmmcall
+    ret
+
-- 
2.17.1


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